1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor substrate having a compound semiconductor layer on a single-crystal silicon layer, and more particularly to a method for manufacturing a semiconductor substrate in which a compound semiconductor layer having an uniform thickness is formed on a single-crystal silicon wafer, so that an interface stress due to a difference in coefficients of thermal expansion between the silicon wafer and a compound semiconductor wafer is reduced by a stress absorbing means to prevent the two bonded wafers from separating.
2. Description of the Prior Art
A prior art method for manufacturing a semiconductor substrate in which a compound semiconductor layer composed of GaAs, InP or the like is formed on a single-crystal silicon wafer is described by V. Lehmann, K. Mitani, R. Stengl, T. Mii, and U. Gosele, "Bubble-free wafer bonding of GaAs and InP on silicon in a microcleanroom", Applied Physics Letters, Vol. 28, No. 12, pages 2141-2143, November 1989.
In such a prior art, since a silicon layer (as a single-crystal silicon wafer) and a GaAs layer (as a compound semiconductor wafer), or a silicon layer (as a single-crystal silicon wafer) and an InP layer (as a compound semiconductor wafer) are different in coefficient of thermal expansion therebetween, there occurs a problem that the two layers bonded by a thermal process is separated from each other at a temperature of 160.degree. C. and more. Separating of the two layers is for lack of an absorbing means for absorbing an interface stress caused by difference in coefficient of thermal expansion therebetween.